Deep Sleep
Sleep h duration
Duration of deep (slow-wave) sleep phase in hours.
Detailed Description
N3 phase (NREM Stage 3) — restorative stage with delta waves. Critical for physical recovery, immune function, and declarative memory consolidation. Normal range is 15–25% of total sleep; declines with age (Mander 2017). Less than 1 hour warrants attention.
How to Improve
- Exercise during the day (but not within 3 hours of bedtime)
- Lower bedroom temperature to 18°C
- Avoid alcohol — it suppresses deep sleep